A controlled potential electrolysis approach for the direct removal of urea in a regenerative hemodialysis system is proposed. Studies in this laboratory have already demonstrated that direct electrolysis of physiologic urea solution into nontoxic products can be achieved at a significant rate under a constant potential condition at +1.00 V vs. Ag/AgCl. A rate of urea removal, 0.22mg/hr/square cm anode in an intermittent potential reversal electrolysis flow-through cell system, has been achieved. It is estimated that 11 pairs of 10 x 22 cm electrodes would be sufficient to remove urea at a rate of about 1 g/hr, which approximates three times the endogenous production. The products have been preliminarily identified as nitrogen, carbon dioxide and water which are nontoxic and eliminatable by ordinary human body functions such as respiration. The electrodes of the device were found to be electrochemically regeneratable. This device will be coupled with an activated charcoal adsorption column for the removal of dialyzable toxins and wastes in a closed-loop regenerative dialysis system. Areas of investigation will include the search for better electrodes including catalysts and current collectors, further studies of intermittent potential reversal electrolysis and other parameters to enhance the rate of urea removal, analysis of electrolysis products, improvement and fabrication of the flow-through cell design and the coupling of the device to a closed-loop hemodialyzer. The feasibility of urea removal at a desired rate, the absence of toxic products from the urea electrolysis or the electrode material itself, the capability of maintaining electrolyte balance, the lack of interference by other dialyzable compounds, the regeneratable nature of the electrodes and finally the "portability" of a device requiring little more than an electrical outlet all have provided the stimulus and justification for further investigation and development.